Re: [CAD_CAM_EDM_DRO] 3 phase motor math

hi Abby
sorry ,nothing about math ,but youe motor can work under
2 phases (neutral + 1 phase ) but you need a starting capacitorto discrimate
the cw or the ccw sense,this is not the best ,because you loose torque.
The best but a little bit more expensive is to find (ebay ?) a vario like
Eurotherm,
altivar(telemecanique) or KEB, these vario can start your motor with a
simple
switch,you can overdrive the motor over the 50/60hz ,a break is include + a
reverse sense.
Few options are provided (not in the same vario !) ;
2phases (220vac)to 3 phases output 380 vac (Eurotherm)
3 phases vac(380vac) to 3 phases output.
you can adjust the ramp for acceleration and deceleration (soft break)
A lot of vario are "obsolets" for their users but not for you..?
the price is "around" 1000 euros for a brand new ,and 100 euros for
an obsolete used (just the size and some unusefull features less).
ou can easily drive these vario with a 10....100khoms trimpot for adjuting
the speed.
(also a controler interface,if you want)
3.5 amp.220vac or 2.0 amp 380vac is not a great value,I'm sure you could
get one easily for a low price.
good luck
thierry


-----Message d'origine-----
De : AbbyKatt <cnc@...>
À : CAD_CAM_EDM_DRO@yahoogroups.com <CAD_CAM_EDM_DRO@yahoogroups.com>
Date : dimanche 16 mai 2004 20:19
Objet : [CAD_CAM_EDM_DRO] 3 phase motor math

>Hi guys,
>
>I have a nice old 3 phase motor I want to hook up to my VFD. I've gone
>through all the motions of opening it up and cleaning it a bit, and
>checking the resistace between windings and ground, and it seems okay.
>What I don't know however is whether it's wired right..
>
>My VFD outputs 220V, so I'd need the motor to be in the Delta
>configuration.
>The motor has the following written on it:
>
>Volts: 220/380-415
>Amps: 3.45 / 2.0
>
>I measured 25ohms between each connection point...
>But the usual V=IR formulas totally don't yield me any answer.. it must
>be because it's 3 phase and AC.
>
>I Googled for 3 phase motor/resistance/amps formulas but only came up
>with a lot of junk people were trying to sell me, and some other stuff.
>How do I work out what voltage this motor is currently configured for?
>
>Thanks!
>-Abby
>
>
>[Non-text portions of this message have been removed]
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